Add support for H.263 video in the RTP muxer

patch by Martin Storsjö (martin AT martin DOT st)

Originally committed as revision 18347 to svn://svn.ffmpeg.org/ffmpeg/trunk

Changelog

@@ -6,6 +6,7 @@ version <next>:
 - VQF demuxer
 - Alpha channel scaler
 - PCX encoder
+- RTP packetization of H.263
 
 
 

libavformat/Makefile

@@ -189,6 +189,7 @@ OBJS-$(CONFIG_RPL_DEMUXER)               += rpl.o
 OBJS-$(CONFIG_RTP_MUXER)                 += rtp.o         \
                                             rtp_aac.o     \
                                             rtp_asf.o     \
+                                            rtp_h263.o    \
                                             rtp_mpv.o     \
                                             rtpenc.o      \
                                             rtpenc_h264.o \

libavformat/rtp_h263.c

@@ -0,0 +1,80 @@
+/*
+ * RTP packetization for H.263 video
+ * Copyright (c) 2009 Luca Abeni
+ * Copyright (c) 2007 Martin Storsjo
+ *
+ * This file is part of FFmpeg.
+ *
+ * FFmpeg is free software; you can redistribute it and/or
+ * modify it under the terms of the GNU Lesser General Public
+ * License as published by the Free Software Foundation; either
+ * version 2.1 of the License, or (at your option) any later version.
+ *
+ * FFmpeg is distributed in the hope that it will be useful,
+ * but WITHOUT ANY WARRANTY; without even the implied warranty of
+ * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the GNU
+ * Lesser General Public License for more details.
+ *
+ * You should have received a copy of the GNU Lesser General Public
+ * License along with FFmpeg; if not, write to the Free Software
+ * Foundation, Inc., 51 Franklin Street, Fifth Floor, Boston, MA 02110-1301 USA
+ */
+
+#include "avformat.h"
+#include "rtpenc.h"
+
+static const uint8_t *find_resync_marker_reverse(const uint8_t *restrict start,
+                                                 const uint8_t *restrict end)
+{
+    const uint8_t *p = end - 1;
+    start += 1; /* Make sure we never return the original start. */
+    for (; p > start; p -= 2) {
+        if (!*p) {
+            if      (!p[ 1] && p[2]) return p;
+            else if (!p[-1] && p[1]) return p - 1;
+        }
+    }
+    return end;
+}
+
+/**
+ * Packetize H.263 frames into RTP packets according to RFC 4629
+ */
+void ff_rtp_send_h263(AVFormatContext *s1, const uint8_t *buf1, int size)
+{
+    RTPMuxContext *s = s1->priv_data;
+    int len, max_packet_size;
+    uint8_t *q;
+
+    max_packet_size = s->max_payload_size;
+
+    while (size > 0) {
+        q = s->buf;
+        if ((buf1[0] == 0) && (buf1[1] == 0)) {
+            *q++ = 0x04;
+            buf1 += 2;
+            size -= 2;
+        } else {
+            *q++ = 0;
+        }
+        *q++ = 0;
+
+        len = FFMIN(max_packet_size - 2, size);
+
+        /* Look for a better place to split the frame into packets. */
+        if (len < size) {
+            const uint8_t *end = find_resync_marker_reverse(buf1, buf1 + len);
+            len = end - buf1;
+        }
+
+        memcpy(q, buf1, len);
+        q += len;
+
+        /* 90 KHz time stamp */
+        s->timestamp = s->cur_timestamp;
+        ff_rtp_send_data(s1, s->buf, q - s->buf, (len == size));
+
+        buf1 += len;
+        size -= len;
+    }
+}

libavformat/rtpenc.c

@@ -42,6 +42,8 @@ static uint64_t ntp_time(void)
 static int is_supported(enum CodecID id)
 {
     switch(id) {
+    case CODEC_ID_H263:
+    case CODEC_ID_H263P:
     case CODEC_ID_H264:
     case CODEC_ID_MPEG1VIDEO:
     case CODEC_ID_MPEG2VIDEO:
@@ -370,6 +372,10 @@ static int rtp_write_packet(AVFormatContext *s1, AVPacket *pkt)
     case CODEC_ID_H264:
         ff_rtp_send_h264(s1, buf1, size);
         break;
+    case CODEC_ID_H263:
+    case CODEC_ID_H263P:
+        ff_rtp_send_h263(s1, buf1, size);
+        break;
     default:
         /* better than nothing : send the codec raw data */
         rtp_send_raw(s1, buf1, size);

libavformat/rtpenc.h

@@ -57,6 +57,7 @@ typedef struct RTPMuxContext RTPMuxContext;
 void ff_rtp_send_data(AVFormatContext *s1, const uint8_t *buf1, int len, int m);
 
 void ff_rtp_send_h264(AVFormatContext *s1, const uint8_t *buf1, int size);
+void ff_rtp_send_h263(AVFormatContext *s1, const uint8_t *buf1, int size);
 void ff_rtp_send_aac(AVFormatContext *s1, const uint8_t *buff, int size);
 void ff_rtp_send_mpegvideo(AVFormatContext *s1, const uint8_t *buf1, int size);
 

libavformat/sdp.c

@@ -177,6 +177,10 @@ static char *sdp_write_media_attributes(char *buff, int size, AVCodecContext *c,
                                      payload_type,
                                      payload_type, config ? config : "");
             break;
+        case CODEC_ID_H263:
+        case CODEC_ID_H263P:
+            av_strlcatf(buff, size, "a=rtpmap:%d H263-2000/90000\r\n", payload_type);
+            break;
         case CODEC_ID_MPEG4:
             if (c->extradata_size) {
                 config = extradata2config(c);